How does one connect Segger J-Link Base to nordic nrf52840

[LuckyGinger]

I am in the development stages of developing a ble application with the nrf52840 nordic chip.

I have come to realize the increasing difficulty of debugging this chip only having access to 4 blinking led's, basic prinf commands, and exactly 2 hardware breakpoints in an IDE that doesn't seem to show the local variables... I am a little frustrated, to say the least, hah.

I have been able to get my hands on a Segger J-Link Base as I was under the impression I could do some deeper debugging. However, the 2x10 ribbon cable on the J-Link Base does not match any of the pin connectors on the nrf52840.

Is the J-Link Base even able to debug the nrf52840? Are there any conversion cables that I also need to acquire? I have scoured the internet for sources or information on debugging the nrf52840 but have not been able to find anything. 

Much appreciation in advance for anyone that can help point me in the right direction.

Thanks

-T

[bjorn-spockeli]

Which IDE are you using? Segger Embedded Studio or Keil uVision? Have you disabled code optimization when you're debugging, otherwise you might not be able to view all the local variables when halting the CPU.

As far as I know the nRF52840 has 6 HW breakpoints.

There is an extensive Logging module in our SDK that supports multiple backends, RTT, UART and a Command-Line Interface(CLI). 

You need a J-Link 9-Pin Cortex-M Adapter, available here from Segger or here from Digikey. The 9-pin 0.05'' Samtec FTSH connector can then be connected to the Debug In header(P18) on the nRF52840 DK

 

 

[LuckyGinger]

I am currently using Segger Embedded Studio. I haven't found where to disable code optimization quite yet but I am still looking.

6 HW breakpoints would be loads better than two, especially if I can view the local variables.

Not to sound cheap, but do you know if together these two options will work?

https://www.adafruit.com/product/2094

https://www.adafruit.com/product/1675

Thank you for your help!

[bjorn-spockeli]

LuckyGinger: Yes, the adapter and the cable from Adafruit will work just as well as the adapter from Segger. 

You set the Optimization Level by right-clicking the Project in the Project Explorer, then select Edit Options. This will open the Options Window, where you can set the settings for either the Release build or the Debug build, or you can alter the Common settings that are inherited by the Release and Debug build configurations. You'll find the Optimization Level under Code -> Code Generation -> Optimization Level